The present invention relates to a resilient torsional coupling or damper structure formed of a plurality of spiral spring plates or discs.
A torsional coupling is generally interposed between a driving shaft or torque input member and coaxial driven shaft or torque output member. This type of device is to permit regulated transmission of rotational torque between the members while filtering out vibrations which may occur in the system, such as in a driveline between a vehicle engine and the transmission acting to drive the wheels of the vehicle.
A conventional torsional coupling or damper generally comprises circumferentially acting resilient means, such as helical springs, which are positioned in axially aligned spring windows formed in two or more plates capable of relative rotation therebetween. When torque is applied to the driving plates, the springs are compressed to resiliently urge rotation of the driven plate. A helical spring damper is conventionally used in a vehicle friction clutch or a lock-up clutch within a torque converter housing to dampen the impulses of the vehicle engine which would otherwise cause undesirable characteristics; e.g., impact loadss, pulsations, noises, etc. in the driveline and/or transmission of the vehicle.
A major problem in present damper designs is the amount of space necessary for the damper structure because of the number of helical springs and their circumference utilized in the structure. Also, these dampers require a substantial number of plates, hub and hub arms and torque input members, as well as the helical springs used singly or in nests of two or three concentric springs. Further, such dampers are costly, and under heavy vibrations, their fit-in parts rattle.
Spiral springs have been utilized for torsional long travel applications such as clocks, small engine starters, toys, etc. They have also been tried for heavy loads such as for automotive clutches, however, difficulties have been experienced in fatigued connections and uncontrollable friction between the layers. The present invention overcomes the complexity and difficulties of prior spring damper structures by using a minimum number of substantially identical compact spiral spring parts to provide the damping action.